Hello, I've heard of Réiltín being used as a name for a woman but I am wondering if it could be used as an endearment as well? I am writing a book and one of the character's name is Stella and I think "little star" would be a cute pet name/endearment for the Irish love interest to call her. And in the vocative would it be "a réiltín"?

Thanks so much!

Yes, Réiltín is used as a name, not a traditional name though.
But I haven’t seen it used as an endearment.
Vocative is "a réiltín" or "a Réiltín" (as a name).

A réiltín, a réiltín, cá bhfuil tú?
Thuas sa spéir i bhfad ar shiúl.
Thuas sa spéir ag lonrú leat.
Gleoite, gléigeal tú mar ré.
A réiltín, a réiltín, cé tú féin?
Abair liom, ní heol dom é.

(Irish version of Twinkle, twinkle, little star)